A B767 FLC OVERSHOOTS THEIR ASSIGNED ALT AT TEJAY ON THE PDZ 4 STAR ARR FOR RWY 25R AFTER A RWY CHANGE AT LAX; CA.

Narrative

WE WERE DSNDING OVER THE PDZ VOR WHILE ON THE PDZ 4 ARR TO LAND ON RWY 25L AT LAX. (CLRNC RECEIVED FROM SOCAL APCH.) WHILE OVER THE PDZ VOR THE CTLR SWITCHED OUR RWY TO RWY 25R. THIS LED TO MAJOR CONFUSION IN OUR COCKPIT! THE CTLR TOLD US TO CONTINUE TO FUELER INTXN (WHICH IS ON APCH TO RWY 25L) AND TO LAND ON RWY 25R. SO NOW WE HAD TO SCRAMBLE FOR OUR APCH PLATES FOR RWY 25R AND THE CAPT ALSO HAD TO REPROGRAM THE FMC FOR RWY 25R. IN THE ENSUING CHAOS WHILE PERFORMING THE TASKS STATED ABOVE; RECONFIRMING WITH THE CTLR THE EXACT CLRNC; DSNDING THE ACFT TO MEET ALL OF THE ALT RESTRS ON THE ARR; AND LOOKING FOR TFC THAT WAS BEING CALLED OUT TO US BY ATC; WE INADVERTENTLY DSNDED TO 11600 FT MSL ABOUT 1 MI BEFORE TEJAY INTXN INSTEAD OF LEVELING OFF AT 12000 FT MSL. IN THE CONFUSION; THE CAPT HAD SET 10000 FT IN THE ALT CAPTURE WINDOW BEFORE WE HAD RECEIVED ALT CAPTURE ON OUR FLT MODE ANNUNCIATOR AND WITHOUT MY CONFIRMATION. THUS; THE ACFT CONTINUED TO DSND INSTEAD OF LEVELING OFF AT 12000 FT. SINCE WE WERE ONLY 1 MI FROM THE INTXN THERE WAS NOTHING THAT WE COULD DO; SO WE PRESSED ON. THERE WAS NOTHING SAID TO US BY THE CTLR AND THERE WAS NO APPARENT TFC CONFLICT. I FEEL THAT THE CTLR WAS TRYING TO DO US A FAVOR BY NOT SLOWING US DOWN; BUT HE ACTUALLY CAUSED US MORE WORK THAN IT IS WORTH. I WISH CTLRS WOULD REALIZE THE INCREDIBLE WORKLOAD THAT IS PLACED UPON PLTS IN BUSY CORRIDORS LIKE LAX WHEN THEY SWITCH RWYS ON US AT THE LAST MIN IN A GLASS AIRPLANE LIKE THE B767. PLEASE GIVE US THE OPTION IF WE WOULD LIKE TO CHANGE RWYS WHEN WE ARE THAT CLOSE IN BECAUSE OF THE HIGH WORKLOAD THAT IS NOW GENERATED FOR A 2 PLT OP.